APPLICATION OF APPLICATION OF

NUMERICAL DISTANCE NUMERICAL DISTANCE

RELAYS RELAYS

A PRESENTATION BYA PRESENTATION BY

OS DEPARTMENTOS DEPARTMENT

ERER--II,KOLKATAII,KOLKATA

FOREWORDFOREWORD

�� Gazette Notification from GOI dated Gazette Notification from GOI dated

09.03.2007 regarding Grid 09.03.2007 regarding Grid

connectivity standards applicable to connectivity standards applicable to

Transmission lines & substationTransmission lines & substation--

PartPart--III(3) stipulates that:III(3) stipulates that:

“Two Main Numerical Distance “Two Main Numerical Distance “Two Main Numerical Distance “Two Main Numerical Distance

protection scheme shall be provided protection scheme shall be provided

on all the Transmission Lines of on all the Transmission Lines of

220KV & above for all new 220KV & above for all new

substations. For existing substations. For existing

substations,this shall be substations,this shall be

implemented in a reasonable time implemented in a reasonable time

frame”frame”

POWERGRID’s compliancePOWERGRID’s compliance

�� “Technology made large populations “Technology made large populations possible; large populations now make possible; large populations now make technology indispensabletechnology indispensable

�� POWERGRID is extensively using POWERGRID is extensively using Numerical relays for protection schemes of Numerical relays for protection schemes of all new Lines & substations.all new Lines & substations.

�� All regional OS departments have All regional OS departments have undertaken retrofitting of old relays with undertaken retrofitting of old relays with All regional OS departments have All regional OS departments have undertaken retrofitting of old relays with undertaken retrofitting of old relays with New generation Numerical relays.New generation Numerical relays.

�� POWERGRID,ERPOWERGRID,ER--II has completed 1II has completed 1stst

stage of retrofitting of Numerical distance stage of retrofitting of Numerical distance protection. The work for the 2protection. The work for the 2ndnd stage is stage is presently being executed.presently being executed.

�� Old static type differential relays for all EHV Old static type differential relays for all EHV Transformers are also being retrofitted with Transformers are also being retrofitted with New Numerical differential protection.New Numerical differential protection.

ADVANTAGESADVANTAGES

� Improves dependability as well

as security

� Has Self checking facility

Offers Very low burden� Offers Very low burden

� More flexible because of

programmable capability

� Adaptive relaying schemes

� Permit Historical data storage

ADVANTAGES…Contd.ADVANTAGES…Contd.

� Fiber optical communication with

substation LAN

� Allow GPS (Geographical

Positioning System) Time stampingPositioning System) Time stamping

� Numerical relays simplify interfacing

with CTs and VTs

� Separate connection is not required,

zero sequence voltages and currents

can be derived inside the processor

ENGINEERS CHOICEENGINEERS CHOICE

� Numerical relays represent

best compromise between:

a) Economy and performance

Dependability and securityb) Dependability and security

c) Complexity and simplicity

d) Speed and accuracy

e) Credible and conceivable

COMPARISON STATEMENTCOMPARISON STATEMENT

Numerical Distance RelayNumerical Distance Relay

main functionsmain functions

A single Numerical distance relay has:

� Distance protection

� Power swing Blocking

� Switch on to fault� Switch on to fault

� Phase-fault (highset) overcurrent protection

� Directional earth-fault protection

� Sensitive earth-fault protection

� Overvoltage and undervoltage protection

SPECIAL FUNCTIONSSPECIAL FUNCTIONS

� Broken conductor detection - To

detect network faults such as open

circuits, where a conductor may be

broken but not in contact with

another conductor or the earth.another conductor or the earth.

� Circuit breaker failure protection -

Generally set to back-trip upstream

circuit breakers, should the circuit

breaker at the protected terminal fail

to trip.

Numerical Distance protectionNumerical Distance protection

Other functionsOther functions

ControlControl

� Autoreclose

� Check synchronising

MonitoringMonitoring

� Voltage transformer supervision

System data

� Sequence of event records

� Fault records

� Disturbance recorder

Existing Numerical Distance Existing Numerical Distance

protection in POWERGRIDprotection in POWERGRID--ERER--IIII

Numerical Differential relayNumerical Differential relay

main functionsmain functionsA single Numerical differential relay has:

�� DIFFERENTIAL PROTECTIONDIFFERENTIAL PROTECTION

……Matching to the vector group

…Stabilization under inrush

(eg:based on the presence of second harmonic componentsharmonic components

…Stabilization under overfluxing conditions

(eg:based on the ratio of the fifth harmonic the ratio of the fifth harmonic to the fundamental wave)to the fundamental wave)

� RESTRICTED EARTH FAULT PROTECTION

� DEFINITE TIME AND INVERSE TIME OVERCURRENT PROTECTION

Numerical Differential protectionNumerical Differential protection

main functions…Contd.main functions…Contd.

� THERMAL OVERLOAD PROTECTION

� OVER-/UNDERVOLTAGE PROTECTION

� OVER-/UNDERFREQUENCY PROTECTION

� OVEREXCITATION PROTECTION

…Overexcitation protection detects …Overexcitation protection detects

impermissible high magnetic flux densitiy in

the iron core of power transformers in case of

increase in voltage and/or decrease in

frequency. Flux density above the rated value

saturates the iron core & result in power

transformer overheating due to large iron

losses.

Numerical Differential Numerical Differential

protection:Other functionsprotection:Other functions

Monitoring

� Voltage transformer

supervision

System dataSystem data

� Sequence of event records

� Fault records

� Disturbance recorder

Existing Numerical Differential Existing Numerical Differential

protection in POWERGRIDprotection in POWERGRID--ERER--IIII

MICOM P-633

RET-670RET-670

7UT613

A TOOL TO SYSTEM A TOOL TO SYSTEM

ENGINEERSENGINEERS

�� Numerical relays provide comprehensive Numerical relays provide comprehensive fault reporting data for the analysis of fault reporting data for the analysis of power system faults and relay operations. power system faults and relay operations.

�� Valuable information from relays Valuable information from relays throughout their grid may be gathered.throughout their grid may be gathered.

After a fault, most precise fault location can After a fault, most precise fault location can �� After a fault, most precise fault location can After a fault, most precise fault location can be reached to narrow the search for be reached to narrow the search for possible damage on the line and to cut the possible damage on the line and to cut the down time for restoration.down time for restoration.

�� Software system for relay fault records can Software system for relay fault records can provide the desired precision to the utility provide the desired precision to the utility personnel. personnel.

FAULT STUDYFAULT STUDY

Disturbance reportDisturbance report--11

�� Complete and reliable Complete and reliable information about disturbances information about disturbances in the primary and/or in the in the primary and/or in the secondary system together with secondary system together with continuous eventcontinuous event--logging is logging is accomplished by the accomplished by the accomplished by the accomplished by the disturbance report functionality.disturbance report functionality.

�� The disturbance report, included The disturbance report, included in the IED, acquires sampled in the IED, acquires sampled data of all selected analogue data of all selected analogue input and binary signals input and binary signals connected to the function blockconnected to the function block

Disturbance reportDisturbance report--22

�� Any change in Digital Inputs or Any change in Digital Inputs or

Analog Thresholds function Analog Thresholds function

blocks may be set to trigger the blocks may be set to trigger the

disturbance recorderdisturbance recorder. .

�� All signals from start of preAll signals from start of pre--fault fault �� All signals from start of preAll signals from start of pre--fault fault

time to the end of posttime to the end of post--fault fault

time, will be in the recording.time, will be in the recording.

�� Every disturbance report Every disturbance report

recording is saved in the IED in recording is saved in the IED in

the standard formats. the standard formats.

Event recorderEvent recorder

�� Quick, complete and reliable Quick, complete and reliable information about disturbances information about disturbances in the primary and/or in the in the primary and/or in the secondary system is vital e.g. secondary system is vital e.g. time tagged events logged time tagged events logged during disturbances. during disturbances. during disturbances. during disturbances.

�� This information is used for This information is used for different purposes in the short different purposes in the short term (e.g. corrective actions) term (e.g. corrective actions) and in the long term (e.g. and in the long term (e.g. Functional Analysis).Functional Analysis).

Time synchronizationTime synchronization

�� Time synchronization source Time synchronization source

selector selects a common selector selects a common

source of absolute time for the source of absolute time for the

IED. IED.

�� This makes comparison of This makes comparison of �� This makes comparison of This makes comparison of

events and disturbance data events and disturbance data

between all IEDs possible.between all IEDs possible.

�� It is done now with the IRIGIt is done now with the IRIG--B B

Protocol available with the GPS Protocol available with the GPS

Clock.Clock.

STATION COMMUNICATIONSTATION COMMUNICATION�� Each IED is provided with a communication Each IED is provided with a communication

interface, enabling it to connect to one or interface, enabling it to connect to one or many substation level systems or equipment, many substation level systems or equipment, either on the Substation Automation (SA) either on the Substation Automation (SA) bus or Substation Monitoring (SM) bus. bus or Substation Monitoring (SM) bus.

�� IEC 60870IEC 60870--55--103 communication protocol103 communication protocol

A single glass or plastic port allows design A single glass or plastic port allows design of simple substation automation systems of simple substation automation systems including equipment from different vendors. including equipment from different vendors. including equipment from different vendors. including equipment from different vendors. Disturbance files uploading is provided.Disturbance files uploading is provided.

�� IEC 61850IEC 61850--88--1 communication protocol1 communication protocol

Single or double optical Ethernet ports for Single or double optical Ethernet ports for the new substation communication standard the new substation communication standard IEC61850IEC61850--88--1 allows intelligent devices 1 allows intelligent devices (IEDs) from different vendors to exchange (IEDs) from different vendors to exchange information and simplifies SA engineering. information and simplifies SA engineering.

Return on InvestmentReturn on Investment

�� Investing on Numerical relays Investing on Numerical relays has greater return as it was not has greater return as it was not required to invest for discrete required to invest for discrete relays line OV/UV,LBB,AR, relays line OV/UV,LBB,AR, FL,DR etc.FL,DR etc.FL,DR etc.FL,DR etc.

�� Failure Rate of Numerical relays Failure Rate of Numerical relays in POWERGRID has been very in POWERGRID has been very small, requiring less small, requiring less maintenance cost.maintenance cost.

Return on InvestmentReturn on Investment

A simple example.A simple example.

�� As per the New tariff regime, Outage of a As per the New tariff regime, Outage of a 420/220/33 KV 315MVA Autotransformer 420/220/33 KV 315MVA Autotransformer results a monetary loss of Rs. 2.5L per results a monetary loss of Rs. 2.5L per Day.Day.

�� Tripping in case of even for extraneous Tripping in case of even for extraneous reasons & not on Transformer fault follows reasons & not on Transformer fault follows Health check test program,requiring a full Health check test program,requiring a full reasons & not on Transformer fault follows reasons & not on Transformer fault follows Health check test program,requiring a full Health check test program,requiring a full day.day.

�� DR print, if available may help detect the DR print, if available may help detect the above & Transformers can be restored above & Transformers can be restored within 10within 10--15 Minutes.15 Minutes.

�� A single event of that order may render A single event of that order may render saving of the amount invested for a new saving of the amount invested for a new Numerical differential protectionNumerical differential protection

POWERGRID & NUMERICAL POWERGRID & NUMERICAL

RELAYSRELAYS

� “Technology does not drive change -- it enables change

�� All new substations in POWERGRID All new substations in POWERGRID are coming with Substation are coming with Substation Automation,which inevitably comes Automation,which inevitably comes Automation,which inevitably comes Automation,which inevitably comes with numerical relays with IEC61850 with numerical relays with IEC61850 Communication protocol.Communication protocol.

�� Automation alongwith Numerical Automation alongwith Numerical relays eventually results in cost relays eventually results in cost effectiveness as well as Better grid effectiveness as well as Better grid security.security.

TYPICAL ARCHITECTURE SUBSTATION AUTOMATION SYSTEM IN

POWERGRID

POWERGRID & NUMERICAL POWERGRID & NUMERICAL

RELAYS.. Cond.RELAYS.. Cond.

�� “Once a new technology rolls over you, if “Once a new technology rolls over you, if you're not part of the steamroller, you're you're not part of the steamroller, you're part of the roadpart of the road

�� For Older stations, POWERGRID is For Older stations, POWERGRID is replacing old & obsolete relays with replacing old & obsolete relays with numerical relays.numerical relays.numerical relays.numerical relays.

�� Competitive bidding for Numerical distance Competitive bidding for Numerical distance relays has resulted an average cost of Rs. relays has resulted an average cost of Rs. 1.5L per relay for the retrofitting work.1.5L per relay for the retrofitting work.

�� In a few cases, repairing of old relays has In a few cases, repairing of old relays has been found costlier than retrofitting with a been found costlier than retrofitting with a new numerical relays.new numerical relays.

ADAPTATIONADAPTATION

�� “Our very survival depends on our ability to “Our very survival depends on our ability to stay awake, to adjust to new ideas, to stay awake, to adjust to new ideas, to remain vigilant and to face the challenge of remain vigilant and to face the challenge of change”change”

�� Control & relay schemes usually came Control & relay schemes usually came from OEM’s like ABB,AREVA, from OEM’s like ABB,AREVA, SIEMENS,ER etc . SIEMENS,ER etc . SIEMENS,ER etc . SIEMENS,ER etc .

�� POWERGRID has achieved expertise in POWERGRID has achieved expertise in adaptation of Numerical relay of Make say adaptation of Numerical relay of Make say “X” to be installed in the C&R scheme of “X” to be installed in the C&R scheme of Make “YMake “Y”.”.

�� However, problem of Lower Making However, problem of Lower Making capacity of the Numerical relays in capacity of the Numerical relays in comparison to the old distance relay had to comparison to the old distance relay had to be solved by incorporating CMR’s of be solved by incorporating CMR’s of suitable capacity.suitable capacity.

LASTWORDLASTWORD

�� “Science and technology “Science and technology revolutionize our lives, but revolutionize our lives, but memory, tradition and myth memory, tradition and myth frame our response.”frame our response.”

�� Numerical relays are here as the Numerical relays are here as the best available technology best available technology best available technology best available technology product as on date.product as on date.

�� The advantages are many & The advantages are many & nobody can deny that the nobody can deny that the Numerical relays came to stay Numerical relays came to stay for years until a further better for years until a further better product replaces them.product replaces them.